MR imaging of acute appendicitis in adults

Acute appendicitis is the most common cause of acute abdominal pain requiring
surgery in adults, typically the adolescent. The main cause of appendicitis is
obstruction of the appendiceal lumen that leads to diminished lymphatic and
venous drainage, which in turn can result in bacterial infection of the
appendiceal wall.
Appendicitis presents with periumbilical pain typically descending to the right
lower quadrant, as well as nausea and vomiting in 50% of the patients. If
presentation is less specific, it can be difficult to differentiate acute
appendicitis from other sometimes non-surgical conditions that result in acute
abdominal pain. In these cases, additional imaging is necessary to avoid delay
of diagnosis or unnecessary surgical intervention. The main complication of a
delayed diagnosis is perforation, which can lead to abscess formation,
peritonitis, and even death. The prevalence of appendiceal perforation in
various adult series ranges from 23% to 73%. Graded-compression US is the
imaging method of choice, and high sensitivity and specificity can be achieved
when employed by experienced examiners. However, the appendix is not always
visible, especially if the appendix has a retrocoecal location or if the
appendix is perforated. When further evaluation is necessary, other
cross-sectional imaging modalities play an important role in diagnosis.
Clinical guidelines advice a CT-scan in case the US is inconclusive. CT
examination in appendicitis has been validated and the number of CT scans
performed in the presurgical diagnosis of appendicitis is increasing rapidly.
However the lifetime risk of radiation-induced fatal cancer is estimated to be
considerably higher for adolescent exposure. There are some publications
describing good results with MR imaging of appendicitis in adults, mainly
involving pregnant patients. The introduction of ultra-fast sequences shortens
the examination time, resulting in a better visualisation of the abdomen,
without exposing the patient to radiation.

Primary Objective: To determine the sensitivity and specificity of MRI in a
consecutive series of adult patients suspected for acute appendicitis
Secondary Objective(s): Is MRI of additional value in adult patients with
inconclusive US? And is Diffusion Weighted Imaging (DWI) of additional value in
the imaging of adult patients with suspected appendicitis.

This will be a prospective study performed at the department of Radiology of
the Medical Center Alkmaar. 100 consecutive adult patients suspected of
appendicitis will undergo ultrasound and MR Imaging.

There is no burden or risk with participation of the study.